Expression of the gene encoding phospholipase A2 group 13 (PLA2G13) was found to be significantly upregulated in hepatocellular carcinoma (HCC) tissue relative to adjacent nonmalignant liver. In a search of public gene expression databases, only one cDNA library was found to contain the sequence encoding PLA2G13 suggesting that the gene is rarely expressed or expressed at very low levels. Since PLA2G13 is a secreted protein, it has potential as a serological marker of HCC. The focus of this proposal is to test this hypothesis by developing antibody based assays for PLA2G13 in order to determine HCC levels in patient sera. In phase I of this project, rabbit polyclonal antibodies to three different synthetic PLA2G13 peptides will be produced. Polyclonal antibodies generated against recombinant human PLA2G13 (rhPLA2G13) will also be obtained from academic collaborators. Using rhPLA2G13 as a standard, serum from HCC patients and normal individuals will be assayed by Western Blot and sandwich ELISA for the presence of the protein. Relative levels of PLA2G13 will be correlated with other parameters including alpha-fetoprotein levels and tumor pathology. As a prerequisite for phase of this project, Institutional Review Board approval will be obtained to acquire more serum samples to better characterize PLA2G13 as a serological marker for HCC.